Bought this for my 7 year old son a couple of weeks ago and been very pleased with the bike.
Putting it together took a few hours - it's not particularly difficult but the instructions aren't specific to this bike so not always accurate and the rotor head complicates things somewhat.
The bike itself looks really nice, my son's friends now consider his to be the coolest bike on the block. It is fairly lightweight (I guestimate about 12kg) however that's without the grinding pegs on which alone weigh over 1.5kg. These things are huge and look like they could stop bullets. Being as they somewhat undo the point of buying a lightweight bike I bought some cheap lightweight pegs off ebay (all 4 weigh about the same as one of the original ones, although they are not as cool).
As this bike is cheap I'm sure that corners have been cut somewhere but so far I can't really see where. The bell broke, but it's just one of those silly little ones that all kids bikes seem to get these days and they all break. Other then that bike seems well made, all works smoothly.
Size wise I would say a 7 year old will only just fit on it - seat doesn't go that low and handle bars and seat are quite a long way apart.
If you are looking for a cheap kids bmx I'd say this fits the bill perfectly.